An MFP (Multifunction Peripheral) forms an image by transferring a visible image onto a sheet. The visible image is formed by using a recording material such as a toner.
The recording material includes a decolorizing recording material (hereinafter referred to as a decolorizing toner), the color of which disappears by heating. A sheet on which an image is formed by the decolorizing toner is heated to a predetermined temperature (hereinafter referred to as a decolorizing temperature), whereby the toner is decolorized and the sheet can be reused.
An image forming apparatus has a function of decolorizing a decolorizing toner. In printing using a normal toner (hereinafter referred to as normal printing), a temperature of a fixing part is set to be higher than that of printing using the decolorizing toner (hereinafter referred to as decolorizing printing). In order to decolorize the decolorizing toner, it is required to set the temperature of the fixing part higher than the temperature of the printing using the normal toner.
Therefore, when the decolorizing printing is performed after the normal printing and decolorizing processing, the decolorizing printing cannot be executed until a temperature drops to a predetermined fixing temperature (e.g., the temperature needed for fixing the toner onto the print medium) so as to prevent an image to be printed from being decolorized. Accordingly, a long period of waiting time is needed until the temperature drops to the predetermined fixing temperature.
Further, each of the operations of normal printing, decolorizing processing, and decolorizing printing cannot be executed until the temperature rises to a predetermined fixing temperature. Therefore, the waiting time until the temperature rises to the predetermined fixing temperature can be long. The above-mentioned problems are not limited to the decolorizing printing. The problems are common to various processes when the fixing temperature is different and requires change.